46
TABLE 9
AIR CONDITIONING SYSTEM TROUBLESHOOTING TIPS
AIR CONDITIONING SYSTEM
TROUBLESHOOTING TIPS
17.7 Subcooling Calculation
1. Measure the liquid pressure at the liquid line service valve.
2. Convert the liquid line pressure to saturated temperature. See Table 8.
3. Measure the liquid line temperature at the liquid line service valve.
4. Compare the liquid line temperature to the saturated temperature.
5. The difference between saturated temperature and liquid line temperature is the
subcooling. Subcooling normal range 9° to 12°.
DISCHARGE
SUCTION
SUPERHEAT SUBCOOLING
COMPRESSOR
PRESSURE
PRESSURE
AMPS
Overcharge
High
High
Low
High
High
Undercharge
Low
Low
High
Low
Low
Liquid Restriction (Drier)
Low
Low
High
High
Low
Low Evaporator Airflow
Low
Low
Low
Low
Low
Dirty Heat Pump
High
High
Low
Low
High
Low Outside Ambient Temperature
Low
Low
High
High
Low
Inefficient Compressor
Low
High
High
High
Low
TXV Feeler Bulb Charge Lost
Low
Low
High
High
Low
Poorly Insulated Sensing Bulb
High
High
Low
Low
High
SYSTEM PROBLEM
INDICATORS
TABLE 8
TEMPERATURE PRESSURE CHART
TEMP
R-410A
(Deg. F)
PSIG
-150
—
-140
—
-130
—
-120
—
-110
—
-100
—
-90
—
-80
—
-70
—
-60
0.4
-50
5.1
-40
10.9
-35
14.2
-30
17.9
-25
22.0
-20
26.4
-15
31.3
-10
36.5
-5
42.2
0
48.4
5
55.1
10
62.4
15
70.2
20
78.5
25
87.5
30
97.2
35
107.5
40
118.5
45
130.2
50
142.7
55
156.0
60
170.1
65
185.1
70
201.0
75
217.8
80
235.6
85
254.5
90
274.3
95
295.3
100
317.4
105
340.6
110
365.1
115
390.9
120
418.0
125
446.5
130
476.5
135
508.0
140
541.2
145
576.0
150
612.8
